A. Switch the logfile of current instance only.
SQL> alter system switch logfile; System altered.
B. Archive the logfile of all the threads in RAC environment.
SQL> alter system archive log current; System altered.
C. Switch the logfile of all the threads in RAC environment (Unpublished , Unofficially ).
SQL>alter system switch all logfile; System altered.
D. Make Checkpoint for all Instances in a RAC environment with single command.
SQL> ALTER SYSTEM CHECKPOINT GLOBAL; (LOCAL is default)